A solid oxide fuel cell (“SOFC”) is an electrochemical device that may be used in, for example, large-scale power generation, distributed power, and vehicular applications. One of the key challenges in developing a SOFC is developing high-performance electrode and electrolyte materials that meet SOFC performance and cost requirements. While there are lists of potential candidate materials for both electrodes and electrolytes, significant efforts are required to optimize material combinations, chemical compositions, processing conditions, and the like. This is especially true as the vast majority of such potential candidate materials are either ternary or quaternary-based.
For example, yttria-stabilized zirconia (“YSZ”) is commonly used as an electrolyte material in SOFCs. However, electrolyte performance is relatively sensitive to the ratio of Y to Zr, and this component ratio must be carefully optimized. The same is true for other potential candidate materials for electrolytes, including Sr-doped CeO2, CGO, and the like. Electrode material composition is also critical to the performance of a SOFC. For example, the composition of LaxSr1-xMnO (3-d) (“LSM”), a common cathode material, may greatly affect its electrical conductivity and electrochemical activity.
Typically, various combinations of elements or components with varying chemical compositions are individually formulated and tested in order to achieve optimal performance for electrode and electrolyte materials, a relatively slow, labor-intensive, and costly process. Thus, what is needed are high-throughput systems and methods that make SOFC-related materials development more efficient. The systems and methods of the present invention use a combinatorial or small-scale approach to achieve the high-throughput fabrication, evaluation, and optimization of electrode and electrolyte materials for use in SOFCs.
Likewise, although SOFCs are a promising technology for producing electrical energy from fuel with relatively high efficiency and low emissions, one of the barriers to the widespread commercial use of SOFCs is their relatively high manufacturing cost. This manufacturing cost is driven primarily by the need for state-of-the-art fuel cells capable of operating at relatively high temperatures (approximately 1,000 degrees C.). Such fuel cells are expensive to manufacture. A reduction in the operating temperature of SOFCs would enable the widespread use of this power generation technology.
One of the barriers to a reduction in the operating temperature of SOFCs is the efficiency of the common cathode material, LSM. At intermediate temperatures, the cathodic polarization of LSM is relatively high, leading to large efficiency losses. Thus, new cathode compositions with lower activation polarizations are needed. However, standard ceramic processing techniques for fabricating new cathode compositions are time consuming and costly. Typically, new powder compositions are synthesized in a plurality of steps, including precipitation, filtration, and calcining. Because the microstructure (i.e., the porosity) of the cathode structure contributes substantially to its performance, careful processing of the powder must be performed in order to produce cathode structures with uniform microstructures. The expense associated with synthesizing such ceramic powders limits the number of cathode compositions that may be fabricated and evaluated.
Thus, what is needed are systems and methods that allow for the rapid synthesis of a large range of cathode compositions on a small scale. The systems and methods of the present invention use continuously varying compositions of inorganic or organic salt solutions, such as nitrates, applied to a porous YSZ structure to rapidly produce sets of compositions suitable for high-throughput screening and analysis.